Deep-drawing tool with integral holding-down device

ABSTRACT

A deep-drawing tool where the holding-down device is incorporated into the punch, and the holding-down device consists of individual punches uniformly on the circumference, where the punches are designed as elastomers.

TECHNICAL FIELD OF THE INVENTION

The field of the invention is a deep-drawing tool.

BACKGROUND OF THE INVENTION

The state of the art here is a deep-drawing tool which consistsessentially of a punch, a holding-down device and a deep-drawing die.

In these prior art deep-drawing tools, the holding-down device ismovable separately from the punch and is intended to sit on the metalsheet to be deep drawn and to hold this metal sheet down, while thepunch moves simultaneously downward and pushes the metal sheet into thedeep-drawing die, shaping it.

With the prior art holding-down devices, there is the disadvantage thatholding-down devices are made of a metal which is impacted by a press ofits own such that this metal sheet is held down with a relatively highpressure.

The design of the holding-down device with a press of its own (presspunch) has, however, the disadvantage that the tool is very expensiveand very costly to produce.

SUMMARY OF THE INVENTION

The object of the invention is thus to more economically produce adeep-drawing tool of the type mentioned at the beginning.

To achieve the object established, the invention is characterized by thetechnical teachings of claim 1.

An essential characteristic of the invention is that the holding-downdevice's is incorporated into the punch of the deep-drawing tool and isnot impacted by a separate punch.

Provision is made in an improvement of the invention that theholding-down device is designed not as a ring, but rather that theholding-down device consists of individual punches disposed uniformlydistributed on the circumference, which punches are designed aselastomers.

They are thus spring punches which preferably are made of an elastomericmaterial which has high resilience. Resilient attachment of theholding-down device is alternatively or additionally possible.

With it, the significant advantage is obtained that it is possible to dowithout a punch drive for the holding-down device, since according tothe invention the holding-down device disposed in the punch itself. Ithas now been discovered that certain materials for the holding-downdevices are best suited to generate an appropriate retaining force onthe metal sheet to be secured, whereby this material is so highlydeformable that with a simultaneously secured metal sheet (with a highhold-down pressure), the punch can penetrate into the necessary formingpath in the die.

A polyurethane foam with a high resilience, of, for example, 50%, ispreferably used as a material for the elastic body.

A plastic material which is adjustable with differing holdingcharacteristics according to requirements is preferably used as thematerial for the brake shoes. Thus, for example, a polyethylene, apolyurethane, or the like may be used as the plastic material. Dependingon the material used, a specific coefficient of friction is obtainedupon contact with the metal sheet to be held.

The use of interchangeable cylindrical holding-down devices yields thesignificant advantage that according to requirements the holding-downdevices, which are designed according to the invention as punches, areheld interchangeably.

Thus, the type of holding-down device may be changed for a complexshaped deep-drawn part, in that, for example, holding-down devices withhigh resilience may be used on one side and holding-down devices withlow resilience may be used on the other, such that high tension and thusa high retaining force is exerted on the deep-drawn part on the sidewith the holding-down devices with low resilience, whereas a lowerretaining force is exerted on the deep-drawn part on the opposite sidewhere the holding-down devices with high resilience are used.

In an additional embodiment of the invention, provision is made that theholding-down device is also provided with brake shoes, which brake shoesadapt to the deep-drawn part.

Thus, it is possible to alter the type and design of the brake shoes.

In a first embodiment, provision is made that each holding-down device(which is designed as a punch) is coordinated with its own brake shoe,which shoe corresponds to the cross-section of the holding-down device.

In another embodiment of the invention, provision is made that the brakeshoe is designed as a surrounding ring on which the holding-down devicessit distributed piece by piece on the circumference. The retentive forcemay be altered by changing the type of material and the dimensions andthe holding-down devices. For this, it is important that the brake shoesbe able to elastically change shape slightly in order to be able toadapt to the surrounding edge of the deep-drawn part.

In the technical teaching reported, deep-drawing machines may thus bebuilt very economically since it is possible to completely do without adedicated drive for the holding-down device.

The object of the present invention results not only from the object ofthe individual claims but also from the combination of the individualclaims with each other. All information and characteristics disclosed inthe documents, including the abstract, in particular the spatial designdepicted in the drawings are claimed as essential to the invention, tothe extent they are new individually/or in combination compared to thestate of the art.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is explained in detail with reference todrawings depicting only one embodiment mode. The drawings and theirdescription disclose additional characteristics and advantages essentialto the invention.

They depict

FIG. 1: a schematic cross-section through a deep-drawing tool in a firstembodiment,

FIG. 2: a schematic top view of the punch,

FIG. 3: a schematic of an embodiment with an annular brake shoe,

FIG. 4: a view corresponding to FIG. 1 through a deep-drawing tool in asecond embodiment,

FIG. 5: the deep-drawing tool according to FIG. 4 in the closed state.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts a deep-drawing tool 1, which consists in known fashion ofa punch 3, which may be driven up and down in the directions of thearrow 12 and which carries a punch tool 4.

The punch tool engages in a forming hole 2 of a die 11 disposed underit, whereby a deep-drawing part 10 is to be deep-drawn by the punch tool4. During this process, holding-down devices 5 sit on the deep-drawingpart 10 on the edge zone around the forming hole 2, whereby eachholding-down device is designed roughly like a punch, which punches maybe round, rectangular, oval or of other shapes and preferably comprisean elastomeric body 6. The holding-down devices are preferably oblongand roughly cylindrical.

This elastomeric body should have a relatively high resilience to ensurethat upon penetration of the punch 3 downward in the direction of arrow12 the elastomeric body 6 is simultaneously so greatly deformed that itexerts a holding-down force on the deep-drawing part 10, but theelastomeric body 6 simultaneously shrinks in size since it is preferablyformed from a plastic foam.

For further improvement of the holding-down force, provision may be madethat a brake shoe 8 be formed on the bottom end of the respectiveelastomeric body 6, which shoe is either glued on as a separate plasticpart or connected mechanically to the elastomeric body.

Provision may also be made that the brake shoe be connected in one piecewith and in the same material as the elastomeric body and had beenproduced in the same foam process with a different hardness.

Here, it is also significant that it is possible to completely dowithout a separately driven holding-down device since the elastomericbodies are disposed distributed piece by piece on the circumference.

Moreover, no distribution on an annular surface is required; instead,the elastomeric bodies may be disposed in their recesses 7 on the bottomend of the punch 3 in any order.

Likewise, the recesses 7 may be applied at different heights or withdifferent depths with the same height of associated holding-down devicesto influence the holding-down force at one point compared to that atanother point.

By disposing the elastomeric bodies 6 in the associated recesses 7, theymay be readily interchangeable and may be replaced according torequirements.

FIG. 2 depicts that a surrounding groove 13 is formed around the punch3, into which groove the aforementioned recesses 7 are formed toaccommodate the holding-down devices 5.

Here, it may be seen that, for example, the holding-down devices aredisposed in the shape of a square or a rectangle around the punch tool4.

FIG. 3 depicts that the brake shoe may be formed not only piece by pieceon the bottom end of the elastomeric body, but that the brake shoe maybe designed as a brake shoe ring 9 on which the holding-down devices 5sit. This brake shoe ring is preferably designed from an elastomericplastic material, which adapts to the surrounding edge in the zone ofthe die 11.

According to FIGS. 4, 5, an irregular distribution of the holding-downdevices 5 in the punch 3 is also possible. The figures show that theholding-down devices 5 according to the invention do not absolutely haveto be applied at the same height. It is, of course, not necessary toapply the holding-down devices in a circle; instead, any geometric shapemay be selected.

In the exemplary embodiment depicted, the holding-down devices 5 areprovided not only with a brake shoe 8, but also with an intermediatepiece 14 which, like the brake shoe 8 may be produced together in onepiece of the material with the holding-down device or producedseparately from it and then attached in a suitable fashion. Thisintermediate piece may, for example, be used to adjust specialcompression and shock-absorbing characteristics of the holding-downdevice 5.

The die 2 is provided on the opposing point with a counter holder 15.

In the exemplary embodiment according to FIGS. 4, 5, provision is alsomade to shape the metal sheet in a first deep-drawing process and then,while the sheet is still in the die, to perform additional shaping usingan additional punch 16.

For this, this additional punch 16 is mounted in the punch 3.

Thus, with the present invention an economically producible and flexiblyuseable deep-drawing tool is provided.

I claim:
 1. A deep-drawing tool, comprising: a plurality of hold-downdevices, which are secured directly on a punch, and a die; saidhold-down devices being held exchangeably on the punch; a hold-downdevice being comprised of a plurality of elastomer bodies wherein saidbodies are selected from a group consisting of elastomer bodies ofdifferent elastomeric strengths; a total desired elastomeric strength ofa said hold-down device being formed by choosing a set of differentelastomer bodies that total-up to said total desired elastomericstrength; a said elastomer body of said set being held exchangeably on asaid hold-down device.
 2. A deep-drawing tool, comprising: a pluralityof hold-down devices, which are secured directly on a punch, and a die;said hold-down devices being held exchangeably on the punch; a saidhold-down device being comprised of a plurality of elastomer bodieswherein said elastomer bodies are provided with a brake shoe; a saidbrake shoe is selected from a group consisting of brake shoes withdifferent braking abilities; a total desired braking strength of a saidhold-down device being formed by choosing a set of different brake shoesthat total-up to said total desired brake strength; a said brake shoe ofsaid set being held exchange ably on a said hold-down device.
 3. Adeep-drawing tool, comprising: a plurality of hold-down devices, whichare secured directly on a punch, and a die; said hold-down devices beingheld exchangeably on the punch; a hold-down device being comprised of aplurality of elastomer bodies wherein said bodies are selected from agroup consisting of elastomer bodies of different elastomeric strengths;a total desired elastomeric strength of a said hold-down device beingformed by choosing a set of different elastomer bodies that total-up tosaid total desired elastomeric strength; a said elastomer body of saidset being held exchangeably on a said hold-down device; a said hold-downdevice being comprised of a plurality of elastomer bodies wherein saidelastomer bodies are provided with a brake shoe; a said brake shoe isselected from a group consisting of brake shoes with different brakingabilities; a total desired braking strength of a said hold-down devicebeing formed by choosing a set of different brake shoes that total-up tosaid total desired brake strength; a said brake shoe of said set beingheld exchangeably on a said hold-down device.